This invention relates to systems designed to measure exposure to ultraviolet radiation.
Mullis, U.S. Pat. No. 5,028,792, describes a system for the visualization of exposure to ultraviolet light radiation, in which a combination of polyvinyl alcohol, an acid sensitive dye, and a bisulfite adduct of an ortho-nitro substituted aromatic aldehyde are provided. This mixture changes from one color to a different color upon exposure to ultraviolet radiation. This color change reflects the effect of ultraviolet light radiation on the aldehyde to cause an increase in acidity. This increase in acidity in turn causes the acid sensitive dye to change color, and thus provide a visual signal of exposure to ultraviolet light. In one example (Example 23) a phototranschromic ink was made by forming a mixture of diethylene glycol, polyvinyl alcohol, an ortho-nitrobenzaldehyde, and bromophenol blue. This ink was applied to paper with a brush.